Knee arthroplasty with modular femoral adapters

Abstract

An arthroplasty system may include a first prosthesis to be fixed to a first bone of a joint, a second prosthesis to be fixed to a second bone of the joint for articulation with the first prosthesis, and one or more adapters to be fixed to the first prosthesis for articulation with the second prosthesis to modify the stability of the second prosthesis relative to the first prosthesis. The system may include one or more articular inserts to be coupled to the second prosthesis for articulation with the first prosthesis and/or the adapter(s). The articular inserts may be fixed or mobile bearing relative to the second prosthesis. Each adapter and corresponding articular insert may modify stability differently.

1 . An arthroplasty system for a joint between a first bone and a second bone, the system comprising:
 a first arthroplasty prosthesis with a receptacle, wherein the first arthroplasty prosthesis is configured to be fixed to the first bone and to articulate against a second arthroplasty prosthesis which is configured to be fixed to the second bone, so as to provide a range of motion between the first and second arthroplasty prostheses; and   an adapter removably fixed in the receptacle, wherein the adapter comprises a first constraint feature for constrained articulation against a complementary second constraint feature of the second arthroplasty prosthesis to modify the range of motion.   
     
     
         2 . The system of  claim 1 , wherein the adapter is insertable into, fixable within, and removable from the receptacle when the first arthroplasty prosthesis is fixed to the first bone. 
     
     
         3 . The system of  claim 2 , wherein the adapter goes into the receptacle along a direction that is generally parallel to a mechanical axis of the first bone when the first arthroplasty prosthesis is fixed to the first bone. 
     
     
         4 . The system of  claim 3 , wherein the receptacle comprises an alcove extending into the first arthroplasty prosthesis along the direction, a first insertion stop feature, and a first removal stop feature, wherein the alcove comprises a non-circular cross-sectional shape perpendicular to the direction;
 wherein the adapter comprises a non-circular exterior cross-sectional shape perpendicular to the direction, a second insertion stop feature, and a second removal stop feature, wherein the adapter exterior cross-sectional shape is complementary to the alcove cross-sectional shape;   wherein when the adapter is in the receptacle, the adapter exterior cross-sectional shape fits closely within the alcove cross-sectional shape, the first and second insertion stop features are engaged to prevent over-insertion of the adapter into the receptacle, and the first and second removal stop features are engaged to prevent unintentional removal of the adapter out of the receptacle, wherein the first and second removal stop features are disengageable.   
     
     
         5 . The system of  claim 2 , wherein the adapter goes into the receptacle along a direction that is generally perpendicular to a mechanical axis of the first bone when the first arthroplasty prosthesis is fixed to the first bone. 
     
     
         6 . The system of  claim 5 , wherein the receptacle comprises an alcove extending into the first arthroplasty prosthesis along the direction, a first insertion stop feature, and a first removal stop feature, wherein the alcove comprises a non-circular cross-sectional shape perpendicular to the direction;
 wherein the adapter comprises a non-circular exterior cross-sectional shape perpendicular to the direction, a second insertion stop feature, and a second removal stop feature, wherein the adapter exterior cross-sectional shape is complementary to the alcove cross-sectional shape;   wherein when the adapter is in the receptacle, the adapter exterior cross-sectional shape fits closely within the alcove cross-sectional shape, the first and second insertion stop features are engaged to prevent over-insertion of the adapter into the receptacle, and the first and second removal stop features are engaged to prevent unintentional removal of the adapter out of the receptacle, wherein the first and second removal stop features are disengageable.   
     
     
         7 . The system of  claim 1 , wherein the first constraint feature comprises a cavity;
 wherein the second constraint feature comprises a protrusion received in the cavity so that when the joint is extended, the second arthroplasty prosthesis has limited translation along a direction that is generally perpendicular to a mechanical axis of the first bone, and so that when the joint is flexed, the second arthroplasty prosthesis has limited translation along a direction that is generally parallel to the mechanical axis of the first bone.   
     
     
         8 . The system of  claim 1 , wherein the first constraint feature comprises a main body coupled to a sleeve by a hinge so that the sleeve rotates relative to the main body about a hinge axis, wherein the sleeve comprises a bore;
 wherein the first constraint feature further comprises a shaft that is fixed in the bore;   wherein the second constraint feature comprises a hole that receives the shaft, so that the shaft rotates within the hole about a central longitudinal shaft axis and translates within the hole along the shaft axis.   
     
     
         9 . An arthroplasty system for a joint between a first bone and a second bone, the system comprising:
 a first arthroplasty prosthesis configured to be fixed to the first bone, wherein the first arthroplasty prosthesis comprises a receptacle;   an adapter removably fixed in the receptacle, wherein the adapter comprises a first constraint feature; and   a second arthroplasty prosthesis configured to be fixed to the second bone, wherein the first and second arthroplasty prostheses articulate together to provide a range of motion between the first and second arthroplasty prostheses, wherein the second arthroplasty prosthesis comprises a second constraint feature that articulates against the first constraint feature to increase stability of the first arthroplasty prosthesis relative to the second arthroplasty prosthesis.   
     
     
         10 . The system of  claim 9 , wherein the adapter is insertable into, fixable within, and removable from the receptacle when the first arthroplasty prosthesis is fixed to the first bone;
 wherein the adapter goes into the receptacle along a direction that is generally parallel to a mechanical axis of the first bone when the first arthroplasty prosthesis is fixed to the first bone;   wherein the receptacle comprises an alcove extending into the first arthroplasty prosthesis along the direction, a first insertion stop feature, and a first removal stop feature, wherein the alcove comprises a non-circular cross-sectional shape perpendicular to the direction;   wherein the adapter comprises a non-circular exterior cross-sectional shape perpendicular to the direction, a second insertion stop feature, and a second removal stop feature, wherein the adapter exterior cross-sectional shape is complementary to the alcove cross-sectional shape;   wherein when the adapter is in the receptacle, the adapter exterior cross-sectional shape fits closely within the alcove cross-sectional shape, the first and second insertion stop features are engaged to prevent over-insertion of the adapter into the receptacle, and the first and second removal stop features are engaged to prevent unintentional removal of the adapter out of the receptacle, wherein the first and second removal stop features are disengageable.   
     
     
         11 . The system of  claim 10 , wherein the adapter is insertable into, fixable within, and removable from the receptacle when the first arthroplasty prosthesis is fixed to the first bone; wherein the adapter goes into the receptacle along a direction that is generally perpendicular to a mechanical axis of the first bone when the first arthroplasty prosthesis is fixed to the first bone. 
     
     
         12 . The system of  claim 11 , wherein the receptacle comprises an alcove extending into the first arthroplasty prosthesis along the direction, a first insertion stop feature, and a first removal stop feature, wherein the alcove comprises a non-circular cross-sectional shape perpendicular to the direction;
 wherein the adapter comprises a non-circular exterior cross-sectional shape perpendicular to the direction, a second insertion stop feature, and a second removal stop feature, wherein the adapter exterior cross-sectional shape is complementary to the alcove cross-sectional shape;   wherein when the adapter is in the receptacle, the adapter exterior cross-sectional shape fits closely within the alcove cross-sectional shape, the first and second insertion stop features are engaged to prevent over-insertion of the adapter into the receptacle, and the first and second removal stop features are engaged to prevent unintentional removal of the adapter out of the receptacle, wherein the first and second removal stop features are disengageable.   
     
     
         13 . The system of  claim 9 , wherein the first constraint feature comprises a cavity;
 wherein the second constraint feature comprises a protrusion received in the cavity so that when the joint is extended, the second arthroplasty prosthesis has limited translation along a direction that is generally perpendicular to a mechanical axis of the first bone, and so that when the joint is flexed, the second arthroplasty prosthesis has limited translation along a direction that is generally parallel to the mechanical axis of the first bone.   
     
     
         14 . The system of  claim 9 , wherein the first constraint feature comprises a main body coupled to a sleeve by a hinge so that the sleeve rotates relative to the main body about a hinge axis, wherein the sleeve comprises a bore;
 wherein the first constraint feature further comprises a shaft that is fixed in the bore;   wherein the second constraint feature comprises a hole that receives the shaft, so that the shaft rotates within the hole about a central longitudinal shaft axis and translates within the hole along the shaft axis.   
     
     
         15 . An arthroplasty system for a joint between a first bone and a second bone, the system comprising:
 an adapter comprising a first constraint feature, wherein the adapter is removably fixable to a first arthroplasty prosthesis, wherein the first arthroplasty prosthesis is configured to be fixed to the first bone; and   a second arthroplasty prosthesis comprising a second constraint feature, wherein the second arthroplasty prosthesis is configured to be fixed to the second bone and to articulate against the first arthroplasty prosthesis;   wherein the second constraint feature articulates against the first constraint feature to increase stability of the first arthroplasty prosthesis relative to the second arthroplasty prosthesis.   
     
     
         16 . The system of  claim 15 , wherein the adapter is fixable to, and removable from, the first arthroplasty prosthesis when the first arthroplasty prosthesis is fixed to the first bone. 
     
     
         17 . The system of  claim 16 , wherein the adapter is fixable to, and removable from, the first arthroplasty prosthesis along a direction that is generally parallel to a mechanical axis of the first bone when the first arthroplasty prosthesis is fixed to the first bone. 
     
     
         18 . The system of  claim 16 , wherein the adapter is fixable to, and removable from, the first arthroplasty prosthesis along a direction that is generally perpendicular to a mechanical axis of the first bone when the first arthroplasty prosthesis is fixed to the first bone. 
     
     
         19 . The system of  claim 15 , wherein the first constraint feature comprises a cavity;
 wherein the second constraint feature comprises a protrusion received in the cavity so that when the joint is extended, the second arthroplasty prosthesis has limited translation along a direction that is generally perpendicular to a mechanical axis of the first bone, and so that when the joint is flexed, the second arthroplasty prosthesis has limited translation along a direction that is generally parallel to the mechanical axis of the first bone.   
     
     
         20 . The system of  claim 15 , wherein the first constraint feature comprises a main body coupled to a sleeve by a hinge so that the sleeve rotates relative to the main body about a hinge axis, wherein the sleeve comprises a bore;
 wherein the first constraint feature further comprises a shaft that is fixed in the bore;   wherein the second constraint feature comprises a hole that receives the shaft, so that the shaft rotates within the hole about a central longitudinal shaft axis and translates within the hole along the shaft axis.